Chain tools are used to insert and remove a chain pin from a roller chain. A conventional chain tool has a bridge feature to hold a roller chain, a backing wall to support a roller chain, a pin used to extract or insert the pin of the chain and a drive screw in which the pin is mounted and which is rotated to provide a force used in extracting or inserting the chain pin.
The conventional chain tools cannot accommodate chains of different internal and external widths, and cannot prevent the pin of the chain tool from bending or snapping due to high loads experienced during use. When using the conventional chain tools, the broken pins are caused by misalignment during operation. The misalignment may be caused by poor positioning of the roller chain in the bridge or from the difficulties in keeping the pin of the conventional chain tool concentric to the drive screw during manufacture and during use. The conventional chain tools have a fixed spacing between the backing wall and the bridge. To account for chains of different widths, namely, single-speed chains, eight-speed chains, nine-speed chains, ten-speed chains, and eleven-speed chains, for example, the conventional chain tools have a bridge that is much more narrow than the internal width of the chain. The addition of ten-speed and eleven-speed chains has stressed the systems having the narrow bridge. A tool having a bridge that is narrower than the internal width of the chain is not precise enough to handle the high tolerance chains. This is because the narrow bridge allows the chain to sit misaligned with the pin and backing wall which leads to damage of the chain or to the pin of the tool. Additionally, the narrow bridge is weak and would likely be damaged if the tool was dropped.
The pin of the conventional chain tools is very susceptible to bending and breaking. This is because the pin is supported only axially and can easily wander on a misaligned chain. This combined with increased press forces required for ten-speed and eleven-speed chains renders the conventional pin system unable to prevent failure. Thus, the conventional chain tools suffer from breakage of tool pin components and incompatibility with chains of varying sizes.